There is substantive evidence that alcohol decreases the amount of attention available for stimulus processing. As a result, drinkers may have impaired information processing and may not perceive all salient cues in their environment. This in turn could lead to poor judgment and an inability to regulate drinking. The proposed study will examine alcohol's effects on attention, as indexed by startle blink modification (SBM), secondary reaction time (RT), and the skin conductance response (SCR). Subjects will be administered either alcohol of approximately .06 g% or no alcohol and instructed to perform a tone-counting task. SBM, SCR and secondary RT will be measured while subjects perform the task. The effects of alcohol during individual stages of processing can be studied using these measures of attention. Alcohol is predicted to decrease the amount of resources available for attention at later stages of processing as indexed by greater degrees of SBM during the processing of tube-attended compared to to-be-ignored stimuli, and by decreased SCR amplitudes and increased RTs during the allocation of attentional resources. early stages of processing, indexed by SBM, are hypothesized to be unaffected by alcohol. These data will provide information regarding when and how alcohol has its effects on information processing, thus clarifying conflicting reports that currently exist, and providing valuable information to clinicians who treat problem drinkers.